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Background: X-linked juvenile retinoschisis (XLRS) is an inherited disease caused by RS1 gene mutation, which leads to retinal splitting and visual impairment. The mechanism of RS1-associated retinal degeneration is not fully understood. Besides, animal models of XLRS have limitations in the study of XLRS. Here, we used human induced pluripotent stem cell (hiPSC)-derived retinal organoids (ROs) to investigate the disease mechanisms and potential treatments for XLRS. Methods: hiPSCs reprogrammed from peripheral blood mononuclear cells of two RS1 mutant (E72K) XLRS patients were differentiated into ROs. Subsequently, we explored whether RS1 mutation could affect RO development and explore the effectiveness of RS1 gene augmentation therapy. Results: ROs derived from RS1 (E72K) mutation hiPSCs exhibited a developmental delay in the photoreceptor, retinoschisin (RS1) deficiency, and altered spontaneous activity compared with control ROs. Furthermore, the delays in development were associated with decreased expression of rod-specific precursor markers (NRL) and photoreceptor-specific markers (RCVRN). Adeno-associated virus (AAV)-mediated gene augmentation with RS1 at the photoreceptor immature stage rescued the rod photoreceptor developmental delay in ROs with the RS1 (E72K) mutation. Conclusions: The RS1 (E72K) mutation results in the photoreceptor development delay in ROs and can be partially rescued by the RS1 gene augmentation therapy. [ABSTRACT FROM AUTHOR]

Pre-mRNA processing factors (PRPFs) are vital components of the spliceosome and are involved in the physiological process necessary for pre-mRNA splicing to mature mRNA. As an important member, PRPF6 mutation resulting in autosomal dominant retinitis pigmentosa (adRP) is not common. Recently, we reported the establishment of an induced pluripotent stem cells (iPSCs; CSUASOi004-A) model by reprogramming the peripheral blood mononuclear cells of a PRPF6-related adRP patient, which could recapitulate a consistent disease-specific genotype. In this study, a disease model of retinal pigment epithelial (RPE) cells was generated from the iPSCs of this patient to further investigate the underlying molecular and pathological mechanisms. The results showed the irregular morphology, disorganized apical microvilli and reduced expressions of RPE-specific genes in the patient's iPSC-derived RPE cells. In addition, RPE cells carrying the PRPF6 mutation displayed a decrease in the phagocytosis of fluorescein isothiocyanate-labeled photoreceptor outer segments and exhibited impaired cell polarity and barrier function. This study will benefit the understanding of PRPF6-related RPE cells and future cell therapy. [ABSTRACT FROM AUTHOR]